Implementing a delegate for wordwrap in a QTreeVie

问题:

I have a tree view with a custom delegate to which I am trying to add word wrap functionality. The word wrapping is working fine, but the sizeHint() seems to not work, so when the text wraps, the relevant row does not expand to include it.

I thought I was taking care of it in sizeHint() by returning document.size().height().

def sizeHint(self, option, index):
    text = index.model().data(index)
    document = QtGui.QTextDocument()
    document.setHtml(text) 
    document.setTextWidth(option.rect.width())  
    return QtCore.QSize(document.idealWidth(), document.size().height())    

However, when I print out document.size().height() it is the same for every item.

Also, even if I manually set the height (say, to 75) just to check that things will look reasonable, the tree looks like a goldfish got shot by a bazooka (that is, it's a mess):

As you can see, the text in each row is not aligned properly in the tree.

Similar posts

Similar issues have come up before, but no solutions to my problem (people usually say to reimplement sizeHint(), and that's what I am trying):

QTreeWidget set height of each row depending on content

QTreeView custom row height of individual rows

http://www.qtcentre.org/threads/1289-QT4-QTreeView-and-rows-with-multiple-lines

SSCCE

import sys
from PySide import QtGui, QtCore

class SimpleTree(QtGui.QTreeView):
    def __init__(self, parent = None):    
        QtGui.QTreeView.__init__(self, parent)
        self.setAttribute(QtCore.Qt.WA_DeleteOnClose)
        self.setGeometry(500,200, 400, 300)  
        self.setUniformRowHeights(False) #optimize: but for word wrap, we don't want this!
        print "uniform heights in tree?", self.uniformRowHeights()
        self.model = QtGui.QStandardItemModel()
        self.model.setHorizontalHeaderLabels(['Task', 'Description'])
        self.setModel(self.model)
        self.rootItem = self.model.invisibleRootItem()
        item0 = [QtGui.QStandardItem('Sneeze'), QtGui.QStandardItem('You have been blocked up')]
        item00 = [QtGui.QStandardItem('Tickle nose, this is a very long entry. Row should resize.'), QtGui.QStandardItem('Key first step')]
        item1 = [QtGui.QStandardItem('<b>Get a job</b>'), QtGui.QStandardItem('Do not blow it')]
        self.rootItem.appendRow(item0)
        item0[0].appendRow(item00) 
        self.rootItem.appendRow(item1)
        self.setColumnWidth(0,150)
        self.expandAll()
        self.setWordWrap(True)
        self.setItemDelegate(ItemWordWrap(self))

class ItemWordWrap(QtGui.QStyledItemDelegate):
    def __init__(self, parent=None):
        QtGui.QStyledItemDelegate.__init__(self, parent)
        self.parent = parent
    def paint(self, painter, option, index):
        text = index.model().data(index) 
        document = QtGui.QTextDocument() # #print "dir(document)", dir(document)
        document.setHtml(text)       
        document.setTextWidth(option.rect.width())  #keeps text from spilling over into adjacent rect
        painter.save() 
        painter.translate(option.rect.x(), option.rect.y()) 
        document.drawContents(painter)  #draw the document with the painter
        painter.restore()
    def sizeHint(self, option, index):
        #Size should depend on number of lines wrapped
        text = index.model().data(index)
        document = QtGui.QTextDocument()
        document.setHtml(text) 
        document.setTextWidth(option.rect.width())  
        return QtCore.QSize(document.idealWidth() + 10,  document.size().height())       

def main():
    app = QtGui.QApplication(sys.argv)
    myTree = SimpleTree()
    myTree.show()
    sys.exit(app.exec_())

if __name__ == "__main__":
    main()

回答1:

The issue seems to stem from the fact that the value for option.rect.width() passed into QStyledItemDelegate.sizeHint() is -1. This is obviously bogus!

I've solved this by storing the width in the model from within the paint() method and accessing this from sizeHint().

So in your paint() method add the line:

index.model().setData(index, option.rect.width(), QtCore.Qt.UserRole+1)

and in your sizeHint() method, replace document.setTextWidth(option.rect.width()) with:

width = index.model().data(index, QtCore.Qt.UserRole+1)
if not width:
    width = 20
document.setTextWidth(width)